Significant interruption in kidney function in an individual can lead to incapacitation or even death. Disease or injury can impair kidney function. An example of an injury that can damage kidneys is ischemic injury. In this type of injury, kidney tissue is damaged because of oxygen deprivation occurring as a result of interruption of blood flow to the kidneys.
Certain agents involved in repair of diseased or damaged kidney tissue, and mechanisms in which the repair takes place, have been described. Mechanisms include induction of gene expression and recruitment of growth factors to the affected kidney tissue. Cell death and cellular proliferation are also associated with repair or kidney tissue.
Agents implicated in kidney tissue repair include polypeptides, e.g., growth factors such as insulin growth factor (IGF), epidermal growth factor (EGF), hepatocyte growth factor (HGF), and the endothelial cell adhesion molecule ICAM-1.
Recently, the polypeptide kidney-injury molecule (KIM-1) has been described. The expression of KIM-1 is increased in injured kidney tissue. The rat and human forms of this protein have been characterized. The KIM-1 cDNA sequence reveals that the KIM-1 protein is a type 1 membrane protein that contains a novel six-cysteine immunoglobulin-like domain and a mucin domain. The KIM-1 protein is a member of the immunoglobulin gene superfamily and most closely resembles mucosal addressin cell adhesion molecule 1 (MAdCAM-1).